Replace grinding with hard cutting, the main problem embodied in how to guarantee access to the desired surface roughness, shape accuracy and machined surface state. Especially when the feed rate and a smaller depth of cut, the radial force is often greater than the main cutting force and tangential force, cutting precision is not easy to control.

Cutting research shows that the elongation hardened bearing steel small, low plasticity, easy to form a good machined surface roughness. If the machine has sufficient rigidity and fixtures, under reasonable conditions can achieve cutting hardened bearing steel nano cutting.

When selecting five different hardness gcr15 bearing steel machining found the workpiece hardness exceeds hrc50, the higher the hardness of the surface roughness, the better. This is because when the workpiece hardness greater than hrc50, cutting force and cutting heat have declined, so the role of thermal expansion and softening effect of the metal cutting process of the workpiece is reduced, helping improve the cutting surface roughness and precision.

When using pcbn gcr15 hardened bearing steel cutting tool was found in tissue state of the workpiece surface and subsurface change, its microstructure is not tempered by white and black layer over tempering layers, Austrian ultrafine grain structure and martensite mixed structure, the surface was white, also called "white layer" and wear due to oxidation, diffusion wear and abrasive wear mechanism of the action of elements in the workpiece subsurface also changed.